A 43-year-old women with central positional vetigo probably due to cerebellar in-farction is reported. The patient complained of positional vertigo and showed positional right-beating nystagmus when her head was tilted toward the left under Frenzel's glasses. The positional nystagmus was characterized by a lack of a latency period after moving to the provocative position and fatigability on repetitive stimulation. Electronystag-mography indicated direction-changing positional nystagmus: in the left-lateral position, there was nystagmus to the right and in the right-lateral position, nystagmus to the left. These findings suggested a central vestibular lesion. MRI demonstrated a small in-farction in the right cerebellar hemisphere. Furthermore, the eccentric rotation test showed an imbalance in otolith-ocular reflex. The results indicated that the central positional nystagmus was induced by a change in otolithic input under disinhibition of the otolith-ocular reflex due to a cerebellar lesion.
